The overall goal of this project is to study the kinetics and mechanisms of milk secretion by examining a variety of conditions and agents which may influence the quality and quantity of milk-specific products secreted by mammary epithelial cells. These mammary epithelial cells are unique in their ability to simultaneously synthesize and secrete triglycerides containing medium-chain length fatty acids, casein and lactose. Methods are now available for obtaining and culturing as monolayers relatively pure populations of mammary epithelial cells free of other cell types, e.g., fibroblasts, adipose cells and blood cells. Quantitative assays have also been developed in our laboratory for the study of synthesis and secretion of milk-specific fats (triglycerides), proteins (casein) and carbohydrates (lactose) by isolated mammary epithelial cells in vitro. Accordingly, it is now feasible to analyze quantitatively for the first time at the cell level details of secretory responses by mammary epithelia to selected components added to the culture medium and to assess the importance of these compounds in vitro as an indication of an in vivo effect. Therefore, our specific objectives will be to (a) clearly define the kinetics of milk secretion in freshly isolated or cultured mammary epithelial cells from pregnant and lactating mice, (b) obtain information on the mechanisms involved in the secretory process(es) and (c) investigate the ability of various nutrients, metabolites, hormones, and pharmacologic agents to alter the normal secretory response. BIBLIOGRAPHIC REFERENCES: Feldman, M.K. and R.C. Foster (1975). Mammary tumor identification using flow-through cytophotometric analysis. Proc. Amer. Assoc. Cancer Research 16: 196 (Abstract). Foster, R.C. and M.K. Feldman (1976). Technique for mammary epithelial cell isolation and cultivation. In: Tissue Culture Association Manual: Techniques, Methods, and Procedures for Cell, Tissue and Organ Culture. V.J. Evans, P. Perry and M.M. Vincent (eds.), pp. 27-30.